A New Hampshire teen with a rare genetic condition that limited her mobility has been able to accomplish things many experts thought she would never be able to do thanks her service dog.

Profiled in an episode of Britain’s Channel 5 documentary Dogs With Extraordinary Jobs that aired Tuesday, 13-year-old Bella Burton was born with a progressive muscle-wasting disease called Morquio syndrome, and was already having difficulties walking when she was 10.

“The pain in her legs and her hips was getting pretty severe,” her mother Rachel told the show. “So we figured that by the time she was 12 or 13, she really wouldn’t be walking much at all and she would be confined to a wheelchair.”

Miraculously, Bella’s condition improved six months after she was introduced to George, a Great Dane, with the Service Dog Project in Ipswich, Mass.

“My leg muscles got really weak and it was hard to walk, but once I got George it kind of forced me to walk,” Bella said.

To Rachel, her first impression of the 130-pound dog was that George seemed formidable alongside her daughter, who weighed only 40 pounds. But, she soon realized that he was just a gentle giant who understood her daughter’s needs.

“George knew what Bella needed and right when she needed it. If she needed to walk slower, George would slow down so that they could walk right side-by-side,” Rachel said.

“If she was having a good day and could walk faster, he would walk faster. He knew what she needed right when she needed.”

With George’s help, Bella isn’t just able to walk on her own, she’s even taken up swimming.